Intra-abdominal pressure (IAP) is an important parameter and prognostic indicator of a patient's underlying physiologic status. Correct IAP measurement is therefore crucial. One simple way of detecting IAP includes the measurement of bladder pressure. In particular, the measurement of bladder pressure via an indwelling urinary catheter system is a simple and effective way of indirectly measuring intra-abdominal pressure. Serial monitoring of bladder pressures is useful in detecting the onset of intra-abdominal hypertension (IAH) and the progression to the more severe condition, abdominal compartment syndrome (ACS). IAH and ACS occur when the abdominal contents expand in excess of the capacity of the abdominal cavity. Causes of IAH and ACS include intraperitoneal blood, interstitial edema from fluid resuscitation, peritonitis, ascites, and gaseous bowel distention. Both IAH and ACS have been primarily associated with trauma patients; however, patients with other pathological conditions are now being recognized as “at risk” for IAH and ACS.
Primary organ systems adversely affected by IAH and ACS include the cardiovascular, renal, pulmonary, gastrointestinal, and central nervous systems. Not only should patients be monitored for physiological changes, but intra-abdominal pressure also must be measured. Several techniques for measuring intra-abdominal pressure have been described in the literature, including a method described by Kron et al. (Kron, Hartman, and Nolan, “The measurement of intra-abdominal pressure as a criterion for abdominal re-exploration.” Ann Surg, 199:28-30, 1984), which is incorporated by reference into this application as if fully set forth herein. These techniques include direct intraperitoneal measurement with a peritoneal dialysis catheter, intragastric measurement via a nasogastric tube, and measurement of pressure via the rectal route or through a urinary catheter system in the bladder. Although the intraperitoneal route is the most direct, the need for insertion of a special catheter into the peritoneum has inherent risks that make this method undesirable for widespread clinical use. Of the remaining options, measurement of bladder pressure via an indwelling urinary catheter system has become the method of choice because of its ease and reliability.
Serial measurements of bladder pressure should be undertaken as part of the examination of any patient at risk for IAH or ACS, and the measurement of intra-abdominal pressure should be correlated with other assessment findings associated with organ system compromise.
The bladder acts as a passive reservoir and accurately reflects intra-abdominal pressure when the intravesicular volume is approximately 100 mL or less. Bladder pressure can be measured easily by using a conventional pressure transducer system connected to the patient's urinary catheter drainage system. Currently, most bladder pressure measurements are done using devices constructed by medical professions on an ad-hoc basis, who must assemble a pressure monitor using materials available in the hospital setting. Such homemade monitors require time to assemble, and may vary in quality and ease of use. Thus, they may be used less frequently than would be beneficial. These monitors do not have a standardized level or performance or sterility. These devices may leak and may require interruption of the closed catheter system. Furthermore, commercially available systems (such as the Wolfe-Tory “AbViser” System) require opening the Foley catheter system to use. An example of such a system may be seen in U.S. Patent Application Publication No. 2006/0058702 to Christensen et al., which is incorporated by reference into this application as if fully set forth herein.
Applicants have recognized that it would be particularly advantageous to provide single or multiple (e.g., serial) measurements of IAP using commercially available urine catheters, such as Foley catheters. Applicants have also recognized that it would be advantageous to perform one or more IAP measurements from a urine catheter that is part of a catheterization system already in use by a patient, without having to open the system (e.g., by detaching the drainage tube, etc.), as opening the catheterization system may result in potentially exposing a patient or medical care provider to contamination or leakage of the system. Accordingly, devices, systems and methods for taking IAP measurements that may overcome one or more of these problems and/or others are described herein.